In the field of welding and in other fields, to protect the eyes of a person automatically darkening lens devices, sometimes referred to as auto-darkening lenses, have been used. Auto-darkening lenses may have, for example, a light shutter that is controllable to control the amount of light transmitted through it, and a light sensitive device and associated control and/or operating circuitry to sense the light that is incident on the light shutter and in response to the sensed light to control the light transmitting characteristics of the shutter. The controllable shutters may be used in welding helmets, respirator helmets and systems, safety eye glasses, regular eye glasses, goggles, and other devices used to protect the eyes of a wearer or user.
In systems that use auto-darkening lenses, such as welding helmets, respirator helmets and systems, safety eye glasses, regular eye glasses, goggles, and other devices used to protect the eyes of a wearer or user, it may be inconvenient or even undesirable to remove the system, e.g., a respirator helmet or welding helmet, to make adjustments to shade number setting, sensitivity, and/or other adjustments. Indeed, in a harsh environment a person may not want to remove a respirator helmet in which an air supply is provided and it also may be difficult to remove the helmet. For example, it is difficult to remove and to reinstall the helmet of a powered air respirator. However, for various reasons, after the system is put on, e.g., a helmet is placed on a user's head, it may be desirable to make adjustments to the operation of the controllable shutter, its operating circuitry, etc.
In prior welding helmets and respirator helmet systems, for example, knobs have been provided on the outside of the helmet system to allow the user to make adjustments while the helmet system is being worn. However, to do this it is necessary to place a hole in the helmet body, for example, to provide for connections with circuitry within the helmet near the user's face. Making the hole is difficult; making the hole may damage the helmet; making the hole may reduce the sealed integrity of a respirator helmet that is intended to protect the user from the external environment. For these reasons, too, it is difficult and may be undesirable to retrofit an existing welding helmet or the like with ability to make adjustments to controls for the auto-darkening lens while the helmet is being worn.
Accordingly, there is a need to facilitate making such adjustments without removing the system in which the auto-darkening lens is used, e.g., helmet, goggles, etc.
Also, users of prior helmets and associated auto-darkening lenses were unable easily to know the settings made by such external adjustment knobs. In the past manual feedback was used to convey to a user that a given setting was made, e.g., the user may know how far he or she turned a given knob; but manual feedback may not be possible or may be inaccurate, especially if a user is wearing welding gloves or the like.
Accordingly, there also is a need to indicate to the user the adjustments or settings made and/or other pertinent information to a welding helmet and/or the auto-darkening lens thereof without having to remove the helmet, etc.
Various light sensitive devices have been used in the past, such as, for example, photocells, photosensors, light sensors, light sensitive solid state devices, such as light sensitive or photosensitive diodes, photosensors, and other devices (collectively devices to sense light will be referred to herein by those terms and/or by other similar representative terms, all of which are considered equivalent).
In an exemplary auto-darkening lens or other systems in which it is desired automatically to control light transmission, a controllable shutter is controlled to respective dark and/or bright or clear states (or modes) and possibly to intermediate states therebetween. The shutter may be, for example, a liquid crystal shutter or some other shutter that controls light transmission, for example, without affecting image characteristics of light transmitted through the shutter. The operating circuitry operates the shutter to assume the respective states, and the light sensor senses light conditions and provides an input to the operating circuitry to operate the shutter in response to the sensed light conditions. The photosensor provides an output representative of that light. The light may be in the visible, ultraviolet, infrared, or some other spectrum range or combination of ranges.
In an exemplary auto-darkening lens the sensor is placed at the front of a support structure or housing in which the shutter is mounted or the sensor may be in the support structure (e.g., housing), which is provided with an access opening to allow light to reach the sensor. The location at which the sensor is mounted on or in the support structure may be selected to allow the light sensor to receive incident light that is representative of light, which impinges on the shutter. It is desirable that the intensity of the light incident on the sensor would be representative of the light incident on the shutter. In an auto-darkening lens or other controllable light shutter device used for welding it is desirable to detect light representing the occurrence of welding and to distinguish such light from ambient light.
In the description herein reference will be made to a lens (also sometimes referred to as “welding lens,” “welding filter,” “shutter,” and the like, and to an automatically darkening lens (sometimes referred to as auto-darkening lens)) that is able to operate automatically to control transmission of light. The lens may be a light shutter type of a device that is able to control light transmission without distorting, or at least with relatively minimal distortion, of the light and the image characteristics carried by the light or represented by the light. Therefore, when a person looks through the lens, the image seen would be substantially the same as the image seen without the lens, except that the intensity of the light transmitted through the lens may be altered depending on the operative state of the lens. The lens may be used in a welding helmet, and the lens may be used in other types of devices, such as goggles, spectacles, face masks, e.g., for industry (such as in an industrial plant or to protect outdoor or indoor electrical workers), for dentistry to protect the face of a dentist in the operative, respirator systems, nuclear flash eye protection devices, and other types of helmets, etc. Such devices usually are employed to protect the face or the eyes of a person, as is known, for example, in the field of welding and in other fields, too. Further, the lenses may be used in various other places to protect workers from bright light that could present a risk of injury.
For the purposes of providing eye protection, usually a welding lens provides light blocking characteristics in the visible, infrared and/or ultraviolet wavelength ranges. The actual ranges may be determined by the components of the lens, the arrangement of those components, and so forth. One example of such a welding lens is U.S. Pat. No. 5,519,522. The lens assembly disclosed in that patent includes several liquid crystal cell light shutters, several plane polarizers, and a reflector or band pass filter, which is able to reflect ultraviolet and infrared electromagnetic energy and possibly also some electromagnetic energy in the visible wavelength range. The several liquid crystal cells, for example, may be birefringent liquid crystal cells sometimes referred to as surface mode liquid crystal cells or pi-cells.
As will be described further below, the present invention may be used in a variable optical transmission controlling device. The device is described in detail with respect to use in a welding helmet. However, it will be appreciated that the device may be employed in other environments and in other devices and systems for controlling transmission of electromagnetic energy broadly, and, in particular, optical transmission. As used herein with respect to one example, optical transmission means transmission of light, i.e., electromagnetic energy that is in the visible spectrum and also may include ultraviolet and infrared ranges. The features, concepts, and principles of the invention also may be used in connection with electromagnetic energy in other spectral ranges.
Examples of liquid crystal cells and shutters (the terms liquid crystal cell and liquid crystal shutter may be used interchangeably and equivalently herein unless context indicates or implies otherwise), lenses using them and drive circuits are described in U.S. Pat. Nos. 5,208,688, 5,252,817, 5,248,880, 5,347,383, and 5,074,647. In U.S. Pat. No. 5,074,647, several different types of variable polarizer liquid crystal devices are disclosed. Twisted nematic liquid crystal cells used in an automatic shutter for welding helmets are disclosed in U.S. Pat. Nos. 4,039,254 and Re. 29,684. Exemplary birefringent liquid crystal cells useful as light shutters in the present invention are disclosed in U.S. Pat. Nos. 4,385,806, 4,436,376, 4,540,243, 4,582,396, and Re. 32,521 and exemplary twisted nematic liquid crystal cells and displays are disclosed in U.S. Pat. Nos. 3,731,986 and 3,881,809. Another type of liquid crystal light control device is known as a dyed liquid crystal cell. Such a dyed cell usually includes nematic liquid crystal material and a pleochroic dye that absorbs or transmits light according to orientation of the dye molecules. As the dye molecules tend to assume an alignment that is relative to the alignment of the liquid crystal structure or directors, a solution of liquid crystal material and dye placed between a pair of plates will absorb or transmit light depending on the alignment of the liquid crystal material. Thus, the absorptive characteristics of the liquid crystal device can be controlled as a function of applied electric field.
As is disclosed in several of the above patents, the respective shutters may have one or more operational characteristics (sometimes referred to as modes or states). One example of such an operational characteristic is the shade number; this is the darkness level or value of the shutter when it is in the light blocking mode (dark state). Another exemplary operational characteristic is the delay time during which the shutter remains in a dark state after a condition calling for the dark state, such as detection of the bright light occurring during welding, has ceased or detection thereof has terminated or been interrupted. Still another operational characteristic is sensitivity of the detection circuit and/or shutter to incident light, for example, to distinguish between ambient conditions and the bright light condition occurring during a welding operation, and sensitivity also may refer to shutter response time or to the time required for the circuitry associated with the lens to detect a sharp increase in incident light (e.g., due to striking of the welding arc, etc.) and to switch the lens from the clear state to the dark state. Even another characteristic, which may be considered an operational characteristic, is the condition of the battery or other power source for the shutter, such as the amount of power remaining, operational time remaining until the power source becomes ineffective, etc. In the past various of the operational characteristics of such shutters have been adjustable or fixed.
Dynamic operational range or dynamic optical range is the operational range of the lens between the dark state and the clear state, e.g., the difference between the shade numbers of the dark state and the clear state.
An example of a “welding lens with integrated display and method” is disclosed in U.S. Pat. No. 6,067,129. In the invention disclosed therein the current operational characteristics of the shutter can be displayed and can be selectively changed by operating one or more switches. The switches may be flexible membrane switches, microswitches, or another type of switch.
The present invention is useful for eye protection by an automatic darkening light shutter in a helmet or goggle assembly or in another device, if desired. The switching mechanism for powering the light shutter on and off and/or for selecting operational characteristics may be an integral part of the light shutter and/or frame assembly or other component or portion thereof.
The light shutter, photosensor arrangement and/or control of the present invention may be used in a variety of embodiments and applications. The shutter is adjustable to control light, i.e., to increase or to decrease the amount of the incident light that is transmitted through the shutter. When welding is not occurring, for example, the shutter in a welding helmet may be substantially optically clear or transmissive or at least minimizes its attenuation of light. When welding is occurring, the shutter may be dark or closed to reduce the amount of light transmitted therethrough in order to protect the eyes of the person performing the welding and to maximize his or her viewing comfort. In both cases, though, the image characteristics of the light preferably remain intact. A photosensitive device may be used to sense the intensity of light impinging in the area of the shutter so as to provide an input to a drive circuit or operating circuitry for the shutter in order to control opening and closing thereof.
The disclosures of the patents identified herein are incorporated in their entirety by reference.